Comparative Study on Functional, Rheological, Thermal, and Morphological Properties of Native and Modified Cereal Flours

High-Resistant Starch Based on Amylopectin Cluster via Extrusion: From the Perspective of Chain-Length Distribution and Structural Formation

Resistant starch (RS) has the advantage of reshaping gut microbiota for human metabolism and health, like glycemic control, weight loss, etc. Among them, RS3 prepared from pure starch is green and safe, but it is hard to achieve structural control. Here, we regulate the crystal structure of starch with different chain-length distributions (CLDs) via extrusion at low/high shearing levels. The change in CLDs in extruded starch was obtained, and their effects on the fine structure (Dm, dBragg, dLorentz, degree of order and double helix, degree of crystal) of RS and its physicochemical properties were investigated by SAXS, FTIR, XRD and 13C NMR analyses. The results showed that the RS content under a 250 r/min extrusion condition was the highest at 61.52%. Furthermore, the crystalline system induced by high amylopectin (amylose ≤ 4.78%) and a small amount of amylose (amylose ≥ 27.97%) was favorable for obtaining a high content of RS3-modified products under the extruding environment. The control of the moderate proportion of the A chains (DP 6-12) in the starch matrix was beneficial to the formation of RS.

Evaluation of the quality and safety of commercial complementary foods: Implications for nutrient adequacy and conformance with national and international standards

Optimal nutrition in early childhood increases growth and development while preventing morbidity and mortality in later life. This study focused on the quality and safety of 32 commercially produced complementary foods collected from supermarkets in Addis Ababa, Ethiopia. The proximate composition (moisture, protein, fat, crude fibre, and ash); and the mineral profile (calcium, iron, zinc, manganese, and magnesium) were determined using the AOAC method. The determination of antinutritional factors (Condensed tannin and oxalate) was done using a UV spectrophotometer. A rapid visco analyzer was used to measure the rheological property. The microbial load of commercially produced complimentary foods was identified using aerobic colony counts for mold and yeast. Labeling practice was evaluated using the WHO and Ethiopian standard tools. The results of proximate compositions were: protein (0.92-18.16 g/100g), fat (0.63-6.44 g/100g), crude fiber (1.04-13.2 g/100g), energy (410-337 kcal/100g), moisture (0.03-17 g/100g), and ash (0.60-4.67 g/100g). The protein and fat content of all the products is below international standards. Only three products met the standards for energy. Moisture and ash contents partially met the requirement, while all of the carbohydrate contents of the products fell under the specified standard. The lowest and highest mineral contents of the products were: Fe (1.38 to 15.10 mg/100g), Zn (0.64 to 6.78 mg/100g), Ca (30.55 to 364.45 mg/100g), Mg (1.2 to 34.2 mg/100g), and Mn (0.80 to 32 mg/100g). Based on these, 21.5% of the foods met the Fe standard, and 31.5% didn't meet the Zn standard. The Ca and Mg of all the products met the requirement. Except for one product, all met standards. The highest and lowest results for the tannin and oxalate content of the products were 49.20 to 90.09 mg/100g and 0.47 to 30.10 mg/100g, respectively and this shows that the products are below the permissible range for tannin and oxalate. The counts of yeast and mold were 0.00-2.95 log10 cfu/g and 0.00-2.91 log10 cfu/g, respectively. Only one product fell below the standard for yeast count, and none of the products showed a mold count that exceeded the standard. The final viscosity was 63.5-3476 RVU, and only 31.25% of the samples fell under the permissible peak viscosity range, of 83-250 RVU. Thus, regular monitoring of the raw material and processing trends and the inclusion of animal sources in the raw material are suggested for having well-enriched complementary foods. Regulatory bodies should also conduct frequent market surveillance to safeguard the health of the consumer.

Functional and thermal properties of yellow pea and red lentil extrudates produced by nitrogen gas injection assisted extrusion cooking

BACKGROUND

There are excellent opportunities for greater incorporation into our diets of pulses, which are rich in proteins and dietary fibers, if their functional properties are modified to fit a wide range of applications in the food industry. The objective of this research was to produce high protein and fiber extrudates from yellow pea and red lentil flours using conventional and N2 gas injection assisted extrusion cooking methods. The effects of process variables on extrudate functional and thermal properties were also investigated.

RESULTS

The cold viscosity of extrudates produced by N2 gas injection were higher than those produced by conventional extrusion, indicating that gas-assisted extrusion does affect the end-product pasting properties. At higher barrel temperatures (150-175 °C) extrudates did not exhibit any thermal transition in their thermograms, and thus their starches were completely gelatinized and proteins completely denatured during extrusion. In general, water solubility of extrudates produced by N2 gas injection was significantly (P < 0.05) higher than those produced by conventional extrusion. Emulsion capacity and stability of yellow pea extrudates were in the range of 44-50% and 42-47%, respectively, and the counterpart values of red lentil extrudates were very similar (in the range of 43-47% and 43-46%, respectively).

CONCLUSION

Nitrogen gas injection assisted extrusion cooking can be used practically in development of pulse extrudates which contain high protein and dietary fiber. This novel and innovative technique is a reliable alternative method to the conventional CO2 gas injection assisted extrusion cooking methods in the snack food and food ingredient industries. © 2019 Society of Chemical Industry.